Synthesis of new chiral sulfinyldiacetic acid derivatives and attempt at chemoselective asymmetric pummerer reaction

Abstract

(RS)-1 (85% ee) was prepared by utilizing a porcin pancreatic lipase-promoted hydrolysis of sulfinyldiacetic acid dimethyl ester (8) which was derived from thiodiacetic acid (7). (RS)-1 (99% ee) and (S S)-1 (99% ee) were readily obtained by methanolysis of (R S,S)-12 and (SS,S)-12 with MeONa in MeOH. (R S,S)-12 and (SS,S)-12 were furnished by chromatographic separation of the diastereomeric mixture, obtained by oxidation of thiodiacetic mono-carboxylic acid (11) with 30% H2O2 followed by dehydrative condensation of the resultant sulfinyldiacetic mono-carboxylic acid with 4(S)-isopropyl-1,3-thiazolidine-2-thione. (RS)-1 (99% ee) was successively treated with (TMS)2NLi, Ac2O, and TMSOTf to give a major chiral-3 product in 75% ee and in a highly chemoselective manner (chiral-3:chiral-2593:7). © 2002 Pharmaceutical Society of Japan.